1. Field of the Invention
The present invention relates to textile machines and, more particularly, to a drawing frame.
2. Description of the Related Art
The method for the processing and spinning of cotton provides for beating and carding of the raw material to produce a sliver of cotton fibers which are to be subjected to drawing.
During the drawing operation, several slivers are joined together to produce a composite sliver having a predetermined count, that is, weight per unit of length, and the fibers of the composite sliver are made parallel to one another by the actual drawing process. This operation may require several successive passes by a single drawing frame or by several drawing frames in cascade until a sliver having the desired count and quality is obtained. With currently available machines and techniques, the slivers are joined together in numbers which may vary from four to eight and, typically, two passes take place by two drawing frames in cascade.
The sliver to be processed, which comes from the carding machines, is supplied to the input of the first drawing frame for the first drawing pass in containers or tubs of dimensions suitable for the structure of the supply members of the drawing frame. The number of tubs to be provided in the input station of the first drawing frame depends on the number of slivers to be joined together.
The sliver output from the first drawing frame is loaded into containers or tubs which are normally smaller than those coming from the cards and which are brought to the second drawing frame for the second drawing pass. The number of tubs to be provided in the input station of the second drawing frame is usually greater than the number of tubs at the input to the first drawing frame. The sliver output from the second drawing frame is loaded into containers or tubs smaller than those coming from the first drawing pass and having dimensions suitable for the structure of the supply members of the machines disposed downstream which, typically, are spinning machines for the subsequent processing of the drawn sliver.
The use of smaller tubs at the output of the second drawing frame than at the input to the first drawing frame is due to the need to supply continuously a number of processing units downstream of the drawing frame which is much larger than the number of carding units.
It is clear from the foregoing that the drawing operation is very critical with regard to the continuity of the production of a spinning plant. In fact, any stoppage of one of the drawing frames, that is, of a single machine, owing to a breakdown or for maintenance not only causes the material coming from the cards to accumulate upstream but also leads to the stoppage of all of the many machines disposed downstream owing to a lack of material to process. In order to minimize the harmful effects of such an event, spare tubs full of processed slivers are normally used at the outputs of both the first and the second drawing frames, with obvious logistical problems owing to the space occupied by the spare tubs and to their handling.